In general, power for operating electric products such as electric home appliances or office equipment is supplied through a power plant, a power transmission line, and a power distribution line.
Such power is supplied from a central power source, not a distributed power source, so that the power spreads in a radial shape from the center to the periphery, which is supplier-centered rather than consumer-centered.
In addition, the supplying of the power is analog and electromechanical, and damage due to an accident is manually undone, and related facilities are manually recovered.
The information about electricity charge can be known only through a power exchange, and thus, it is difficult to know the information about electricity charge in real time. In addition, since a pricing system is substantially fixed, it is difficult to provide incentives for consumers by using price variations.
To address these limitations and improve the efficiency of energy, researches are being actively carried out on a power network, which can realize a flexible power control. The power control may include a consumption reaction control or an intelligent power control.
As described above, the current power network is vertical and centralized network that is controlled by a supplier, but the consumption reaction control or the intelligent power control is a cooperative and distributed network that allows for interaction between suppliers and consumers.
When the flexible power control is realized, for power consumers such as a house or a building, it is needed that a separate electric product and a network connected to a plurality of electric products communicate with a power supply source through a two-way communication for power information, instead of just receiving power. Also, devices for the two-way communication are needed.